In recent years, concern about quality of living and working environment is risen, so that advanced analytical methods for measuring the composition and concentration of fine particles present in the atmosphere are sought. Further, in industries such as a semiconductor industry in which increased purity of material gases and atmosphere gas control in the manufacturing process are required, it is required to perform highly accurate analysis of the material gases containing fine particles and atmosphere gases in a simple manner.
Accordingly, analysis of analytical samples such as fine particles contained in a sample gas and specific gas components has been performed with analytical devices using highly sensitive analytical methods such as a gas chromatography spectrometry (GC-MS), an inductively coupled plasma analysis method (ICP method), and a microwave induced plasma analysis method (MIP method). For example, in the ICP method and MIP method, the analysis is performed by generating high-temperature plasma by using argon gas, nitrogen gas, helium gas and the like as a plasma gas, introducing an analytical sample into the plasma, and detecting signal variations from the plasma.
In order to analyze accurately the analytical sample contained in such sample gas, a pretreatment device is necessary that performs the pretreatment of removing unnecessary components from the sample gas. For example, when a sample gas containing a gaseous analytical sample is used, moisture, impurity gas components and the like other than the analytical sample contained in the sample gas are required to be removed as unnecessary components. Further, when a solution in which an analytical sample is dissolved in a solvent is converted into droplets floating in a spraying gas with a sprayer or the like and the spraying gas is used as the sample gas, it is required to remove moisture, solvent vapor and the like contained in the sample gas as unnecessary components.
A gas replacement device, a fine particle classification device, a drier or the like is used as the pretreatment device. For example, in the gas pretreatment device described in Patent Document 1, a sample gas is generated by converting a solvent having an analytical sample dissolved therein into a mist with a sprayer, the sample gas is heated to separate droplets into solvent vapor and an analytical sample, the sample gas is introduced in a tubular sealed filter made from a porous material, and the solvent vapor is removed by diffusion to the outside of the sealed filter. In the fine particle classification device described in Patent Document 2, in the process of electrically charging and classifying fine particles that are an analytical sample contained in the sample gas, gaseous contaminating components contained in the sample gas are removed and the fine particles are suspended in an atmosphere composed of a desired gas species. In the drier described in Non-patent Document 1, a sample gas is generated by converting an aqueous solution having an analytical sample into a mist, and moisture contained in the sample gas is removed via a non-porous membrane made of Nafion (trade name of Du Pont Co.; copolymer of perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic and tetrafluoroethylene).
A flow rate of gas containing an analytical sample introduced into an analytical device is changed correspondingly to the type or the like of elements constituting the analytical sample, in order to satisfy the optimum analytical conditions. For example, in a high-sensitivity analysis using plasma, in order to analyze a plurality of elements that are the objects of analysis and contained in the analytical sample, automatic tuning is performed to switch automatically the flow rate of gas introduced together with the analytical sample into the plasma. Further, in the mass analysis using the ionization action of plasma, the flow rate of gas introduced into plasma is automatically changed so as to prevent polyatomic ions having a mass number equal to that of the element that is an object of analysis from hindering the analysis.    Patent Document 1: Published Japanese Translation of a PCT Application No. H7-500416.    Patent Document 2: Japanese Patent Application Laid-open No. 2001-239181.    Non-patent Document 1: Journal of Analytical Atomic Spectrometry, January 1998, vol. 13 (13-18).